docs: def enable_chimera_inline():
      """
      Enable IPython magic commands to run some Chimera actions
  
      Currently supported:
      - %chimera_export_3D [<model>]:
          Depicts the Chimera 3D canvas in a WebGL iframe. Requires
          a headless Chimera build and a Notebook instance. SLOW.
      - %chimera_run <command>:
          Runs Chimera commands meant to be input in the GUI command line
      """
  
      from IPython.display import IFrame
      from IPython.core.magic import register_line_magic
      import chimera
      import Midas
  
      @register_line_magic
      def chimera_export_3D(line):
          if chimera.viewer.__class__.__name__ == 'NoGuiViewer':
              print('This magic requires a headless Chimera build. '
                    'Check http://www.cgl.ucsf.edu/chimera/download.html#unsupported.',
                    file=sys.stderr)
              return
          models = eval(line) if line else []
  
          def html(*models):
              if models:
                  for m in chimera.openModels.list():
                      m.display = False
                  chimera.selection.clearCurrent()
                  for model in models:
                      model.display = True
                      chimera.selection.addCurrent(model)
                      chimera.runCommand('focus sel')
              chimera.viewer.windowSize = 800, 600
              path = 'chimera_scene_export.html'
              Midas.export(filename=path, format='WebGL')
              return IFrame(path, *[x + 20 for x in chimera.viewer.windowSize])
          return html(*models)
      del chimera_export_3D
  
      @register_line_magic
      def chimera_run(line):
          if not line:
              print("Usage: %chimera_run <chimera command>", file=sys.stderr)
              return
          chimera.runCommand(line)
      del chimera_run